Delivery of tractive force to vehicle wheels must be accomplished as smoothly as possible. For example, launching a vehicle to provide tractive force at the vehicle wheels should be done without abrupt changes in torque that will be noticeable to the vehicle occupants. A fluid coupling such as a torque converter may be used to provide such a “soft-lockup” launch. Torque converters are relatively large, and require a hydraulic supply to operate.
Limited slip differentials allow some angular velocity, also referred to as slip, between vehicle wheels, but lockup at a predetermined slip. A smooth lockup of the limited slip differential will smooth torque spikes to improve passenger comfort.